n-ZnO/LaAlO_3/p-Si heterojunction for visible-blind UV detection

Abstract

A visible-blind UV photodetector (PD) using a double heterojunction of n-ZnO/LaAlO3 (LAO)/p-Si was demonstrated. Inserted LAO layers exhibit electrical insulating properties and serve as blocking layers for photoexcited electrons from p-Si to n-ZnO, leading to an enhanced rectification ratio and a visible-blind UV detectivity of the n-ZnO/LAO/p-Si PDs due to the high potential barrier between LAO and p-Si layers (~2.0 eV). These results support the use of n-ZnO/LAO/p-Si PDs in the visible-blind UV PDs in a visible-light environment.

Narrowband, Visible-Blind UV-A Sensor Based on aMg0.52Zn0.48OFilm Deposited by Radio-Frequency Sputtering Using a ZnO-Mg Composite Target

“…The UV/visible rejection ratio, defined here as the ratio of the photocurrent at 400 nm to that at 340 nm, was greater than two orders of magnitude. This value is comparable to or better than those obtained in the TiO 2 -based UV-A detector [9], the ZnO/LaAlO 3 UV-A detector [10], and the epitaxial MgZnO UV photoconductive detector [14]. Figure 7 shows the peak responsivity as a function of the applied bias voltage.…”

“…To achieve visible-blind sensors, the cut-off wavelength for photosensitivity must be near 400 nm. Tsai et al [9] reported visible-blind PDs fabricated using TiO 2 nanowires and n-ZnO/LaAlO 3 [10]. The TiO 2 nanowire had a cut-off wavelength of ca.…”

Semiconductor ultraviolet photodetectors based on ZnO and MgxZn1−xO

“…However, the visible light generated electrons are effectively blocked by the potential barrier and recombined with holes, without generating photocurrent (figure 21(b)). A similar device structure has also been fabricated with LaAlO 3 or SiO 2 as the insulating layer [174,175]. [176].…”

Visible-Blind UV Photodetector Based on Single-Walled Carbon Nanotube Thin Film/ZnO Vertical Heterostructures

“…ZnO is a wide bandgap semiconductor with a direct bandgap of 3.37 eV matching the spectral range desired for solid-state ultraviolet (UV) photodetectors for civil and military applications such as flame detection, UV-level monitoring for public health, intersatellite communication, early-warning missile detection, and engine flame control. − Schottky barrier types of ZnO photodetectors have some advantages over bulk ZnO photoconductors because of the built-in electric field efficiently separating the photoexcited electron–hole pairs before they recombine, and the performance of such devices has been improved by introducing an interdigitated electrode configuration. − p–n homojunction photodiodes are also utilized to generate a built-in electric field, but in the case of ZnO, this option is limited as a reliable growth technique for p-type ZnO is still under development. ,− The closest alternative to the ZnO p–n junction photodetector is a heterojunction device in which n-type ZnO is combined with a p-type conventional semiconductor, typically of a smaller bandgap, such as Si, Ge, or GaAs. − Such a heterojunction was shown to provide a high built-in electric field sufficient for the separation of photogenerated electrons and holes and a satisfactory photodetector performance, but an additional interface layer was needed to preclude unwanted visible spectral range sensitivity . In addition to bulk ZnO layers, nanostructured forms of ZnO, such as nanoparticles and nanowires, have been explored, − showing improved performance in terms of higher UV responsivity, ,,,,, and in some cases, faster response time. − ,,, Despite these recent advances, inorganic wide bandgap semiconductor-based UV photodetectors with visible blindness and fast response times still dominate the commercial market.…”